While simply copying the JA2 aiming system was easy, we never set out to clone JA2. And in some aspects that would be pretty useless. An isometric 2D world has completely different rules from a 3D environment. It's a long list of differences you can all guess.
But to the raised point about mouse aim, in internal tests we found that due to the complex camera maneuvers you need to perform in a 3D world the attaching everything to the mouse can lead to unfortunate mishaps, like firing your gun instead of moving or moving instead of firing your gun. So we had to put movement on RCLICK (the "increase aim" in JA2). The current system isn't perfect but it's the best compromise we found.
Agreed that copying JA2 makes no sense in 3D, I was just reacting to calling JA2 clunky. I feel like US is not better in that regard and in some aspects even worse.
If I remember correctly, in the demo it was hold shift, click the enemy to pop up the radial menu, click again on bodypart to shoot.
That's two left clicks and a keypress.
If I'm holding shift to indicate I want a targeted shot and my mouse moves over a target, why do I still have to click to open the menu?
Anyway I'm not a designer, just saying that even compared to JA2, some aspects of US feel clunky.